Electrical switch



Aug. 8, 1967 A. F. ROMANOWSKI ELECTRICAL SWITCH 2 Sheets-Sheet 1 Filed June 17, 1965 FIQZ JZ/vE/vmw- ALBERT F. ROMANOWSKI 14 awe/(117754 g- 8, 1967 A. F. ROMANOWSKI 3,335,246

ELECTRICAL SWITCH Filed June 17, 1965 2 Sheets-Sheet 2 JA/ l/E/V TO ALBERT F. ROMANOWSKI itc 3,335,246 Patented Aug. 8, 1967 ice 3,335,246 ELECTRICAL SWITCH Albert F. Romanowski, Greeneville, Tenn., assignor to Bowser, Inc, Greeneville, Tenn., a corporation of Indiana Filed June 17, 1965, Ser. No. 464,795 Claims. (Cl. 200152) ABSTRACT OF THE DISCLOSURE The invention provides an explosion-proof switch having a metallic tubular housing containing a sealed mercury switch positioned within the tubular housing and spaced from its inner surfaces by a mounting element. The housing containing the mercury switch and mounting element is filled with a potting material that is held firmly in position by an internal groove in the tubular housing.

This invention relates to an improved electrical switch, and more particularly to an improved electrical switch which is adapted for use in conjunction with apparatus which is in proximity with explosive materials. In the art of dispensing gasoline, it was previously essential that the switch contacts and actuating shafts or linkages be enclosed within explosion-proof boxes or the like. For safety reasons, it must be provided that a spark produced in switch operation will not lead to igniting any volatile explosion-producing gases external to the switch.

Prior arrangements of switches required rigid mounting of the actuating means to provide accurate matching of contacts. To eliminate inadvertent short circuiting and sparking, flameproof enclosures were extended over the actuating means to protect against the severe consequence of sparking, should it occur. The enclosure limited access of explosive fumes to the contact region and further limited propagation of flame or explosion within the enclosure owing to fumes entering the enclosure. Seals were built in the enclosure portions surrounding the movable actuating means in a manner so as not to interfere with the mechanical action of the switch. The enclosures required have necessarily been large, cumbersome and ex pensive in order to provide protection without interfering with switch actuation.

One of the principal objects of the present invention is to provide a novel switch contact housing structure and actuating means which are inexpensive to produce and safe in regard to explosion hazard. In place of the previously used actuating means which are flameproof and which require access covers and are rigidly mounted, the present invention contemplates the use of hermetically sealed switch contacts which are themselves explosionproof and which are readily operable with simple nonrigid devices which do not in themselves require flameproofing.

A further object of the present invention is to provide a novel combination of switch and switch-operating means for use in an environment which is subject to explosions, a switch which, by reason of its simplified structure and its ready servicing, is substantially less expensive to produce and to maintain than previously used switch structures. Use of the novel contact-housing structure eliminates the requirement for extending the flameproofin-g over the actuating means by providing self-contained sealing contacts, and eliminates the requirement for rigid mounting of the actuating means by reducing the precision of matching contacts formerly required.

It is an important feature of the present invention that by utilizing a hermetically sealed mercury switch readily mountable upon a switch-operating arm, it is possible to operate electrical systems on gasoline dispensing appaand replaced with another switch without extensive changes.

Other objects and features of the present invention will become apparent from a consideration of the following description, which proceeds with reference to the ac companying drawings, wherein:

FIGURE 1 is a perspective view of the switch assembly with a portion of the capsule broken away to illustrate the interior structure of the switch;

FIGURE 2 is a perspective view of the switch capsule and switch-operating mechanism, a part of the mounting structure for the operating mechanism being broken away to better illustrate the operating mechanism;

FIGURE 3 is an exploded perspective view of the switch capsule including the mercury switch, housing and mounting structure;

FIGURE 4 is a longitudinal section view of the switch capsule in an off position; and

FIGURE 5 is the same view as FIGURE 4 but showing the switch operated from the angular position of FIGURE 4 to an angular position effecting on operation of the switch.

Referring now to the drawings, the switch assembly designated generally by reference numeral 10 is in the form of a switch capsule having a housing 12 of aluminum or other suitable material of construction with a closed end 14. Within the interior of the housing 12 are a pair of interfitted mounting elements 16, 18 having notches 20, 22, respectively (FIGURE 3), whereby the two parts are fitted together such that the base sections 26, 28 are brought in flush interlocking relation.

The projecting arms 30, 32 of element 16 and arms 34, 36 of element 18 are spaced approximately degrees from each other so that when the two elements are interlocked these provide the mounting surfaces for a mercury switch 38 which includes contacts 40; 42, closable by mercury 44 in the angular position of the switch indicated in FIGURE 5. The globule of mercury 44 is confined within a sealed enclosure 46, permitting the mercury to move from the switch-opening position (FIGURE 4) to switch-closing position (FIGURE 5).

A pair of conductors 48, 50' are connected in series through the contacts 40, 42 when the globule of mercury 44 provides an electrically closed path (FIGURE 5) between the two contacts 40, 42. The conductors 48, 50 extend through complementary openings 53, 54 in an enclosure 56 which is fitted into the end 54 of the housing 12 which is filled with a suitable potting material 57.

The switch capsule is releasably mounted in clips 58, 60 which are mounted on a bracket 62 at the end of a shaft 64 journaled in'an opening 66 of a mounting member 68, The shaft 64 can move angularly and thereby tip the angular position of the switch between the positions shown in FIGURE 4 and FIGURE 5 to produce switch closing and opening.

The shaft 64 has a stop 70 in the form of a pin which is passed through the shaft 64 and is drawn against the mounting structure 68 by a loaded helical spring 72 which is compressed between a shoulder 78 and side 76 of the mounting structure 68. When the switch is moved from FIGURE 5 to FIGURE 4 or vice versa, the pin 70 must be cammed over a convexly-shaped boss 74 against the resistance of the spring 72, and after it is passed over the boss 74, the pin 70 engages one of a pair of stops on the mounting structure 68 thereby to define and maintain one or the other of the angular positions for the switch (FIGURE 4 or FIGURE 5).

The interior of the switch is hermetically sealed by reason of the complete enclosure defined by housing 12, enclosure 56 and the potting material 57 which completely surrounds the mercury switch 38. The switch opening and closing, even if it should produce sparking, presents no danger of an explosion because of the closed environment surrounding the switch contacts 40, 42.-

Should the capsule assembly require servicing, it is replaced in toto by removing it from the clips 58,60 and inserting a new switch capsule, thus facilitating the matter of servicing.

It can be seen from the foregoing description that in place of elaborate and, therefore, expensive explosionproof boxes, which are normally used in hazardous area, there is utilized a much simplified structure which is more economical to produce and to maintain and still possesses all of the safety features which were previously provided in large explosion-proof boxes. Moreover, the switch capsule is non-rigidly mounted and can be disposed at any accessible, convenient location.

It may be desirable in some embodiments of the invention to employ a swivelled conduit where the leads for the switch must also be enclosed, and such arrangement is, of course, well within the teaching of the present invention.

Instead of using rigidly mounted switch means surrounded by sealed enclosure means which are designed to exclude explosive gases, the present invention utilizes sealed switch means which are readily locatable whereever conveniently needed.

As a result of the foregoing, manufacturing costs are substantially reduced, and the safety element is even greater with the foregoing described improved structure.

Although the present invention has been illustrated and described in connection with a single example embodiment, it will be understood that this is illustrative of the invention and is by no means restrictive thereof. It is reasonably to be expected that those skilled in this art can make numerous revisions and adaptations of the invention, and it is intended that such revisions and adaptations which incorporate the herein disclosed principles will be included within the scope of the following claims as equivalents of the invention.

I claim:

1. An improved electrical switch for use in an explosive atmosphere such as gasoline dispensers and the like, comprising:

(a) an elongated, metallic, tubular housing having one closed end and having a groove positioned in the interior surface of said housing near theother end thereof;

(b) a mounting element positioned in said tubular housing, said mounting element being supported by said interior surface and said one closed end of said housing and providing a positioning structure spaced from said interior surface and said one closed end of said housing;

(c) a mercury switch comprising a closed chamber containing a pair of spaced electrodes, a quantity of mercury, and leads respectively connected to said spaced electrodes and extending through a wall of said closed chamber to the exterior thereof;

((1) said mercury switch being positioned in said positioning structure of said mounting element and held thereby in spaced relation from said interior surface and said one closed end of said housing, said leads extending from said mercury switch through said other end of said tubular housing to the exterior thereof;

(e) and a potting material positioned in said tubular housing, said potting material completely surrounding said mercury switch chamber and filling the interior of said tubular housing and said groove to hermetically seal said mercury switch and said other end of said tubular housing.

2. The improved switch of claim 1 wherein said tubular housing is substantially cylindrical in shape.

3. The improved switch of claim 1 wherein said leads are provided with an electrically insulating material exteriorly of said closed chamber.

4. The improved switch of claim 1 wherein said tubular housing is substantially cylindrical in shape and wherein said leads are provided with an electrically insulating material exteriorly of said closed chamber.

5. The improved switch of claim 1 wherein said mounting element comprises two flat members interconnected at substantially right angles relative to each other.

References Cited UNITED STATES PATENTS 2,843,705 3/1955 Kalafsky 200-452 X ROBERT K. SCHAEFER, Primary Examiner.

H. HOHAUSER, Assistant Examiner. 

1. AN IMPROVED ELECTRICAL SWITCH FOR USE IN AN EXPLOSIVE ATMOSPHERE SUCH AS GASOLINE DISPENSERS AND THE LIKE, COMPRISING: (A) AN ELONGATED, METALLIC, TUBULAR HOUSING HAVING ONE CLOSED END AND HAVING A GROOVE POSITIONED IN THE INTERIOR SURFACE OF SAID HOUSING NEAR THE OTHER END THEREOF; (B) A MOUNTING ELEMENT POSITIONED IN SAID TUBULAR HOUSING, SAID MOUNTING ELEMENT BEING SUPPORTED BY SAID INTERIOR SURFACE AND SAID ONE CLOSED END OF SAID HOUSING AND PROVIDING A POSITIONING STRUCTURE SPACED FROM SAID INTERIOR SURFACE AND SAID ONE CLOSED END OF SAID HOUSING; (C) A MERCURY SWITCH COMPRISING A CLOSED CHAMBER CONTAINING A PAIR OF SPACED ELECTRODES, A QUANTITY OF MERCURY, AND LEADS RESPECTIVELY CONNECTED TO SAID SPACED ELECTRODES AND EXTENDING THROUGH A WALL OF SAID CLOSED CHAMBER TO THE EXTERIOR THEREOF; (D) SAID MERCURY SWITCH BEING POSITIONED IN SAID POSITIONING STRUCTURE OF SAID MOUNTING ELEMENT AND HELD THEREBY IN SPACED RELATION FROM SAID INTERIOR SURFACE AND SAID ONE CLOSED END OF SAID HOUSING, SAID LEADS 